iPhone X microphone during a phone call

My iPhone X has been fine until i changed carrier to Vodaphone so that I could add apple watch 5 to my plan .... currently the watch isn't recognised by the plan or vice verso BUT more worryingly my phone microphone doesn't work during phone call so i cat get help !

If i use an app like WhatsApp the microphone is perfect or to record a voice memo but as soon as I make a phone call no one can hear e, the same even if I use blue tooth to connect to my car no microphone ?

Any ideas please ?

phone is on latest firmware and so is the watch and they have been disconnected and reconnected tried with one or the other switched off